Cfi£vnistry and Mineralogy. 421 



mediately be seen which of them had heen reihai kable for heat, 

 rain, steadiness, or the contrary. 



A paper Was read by Mr Alexander J. Adie, civil engineer, 

 Edinburgh, on experiments made with a pyrometer heated by a 

 current of steam on the expansion of stone and other substances. 

 The quantities were measured by a micrometer, which reads the 

 thirty-thousandth part of an inch, and given in decimals of the 

 length for 180° F. He found that when a rod of straight-grained 

 well seasoned oak was kept dry, it only expanded at about the fif- 

 teenth part of the rate of platinum ; that the expansion of black 

 marble was about half as much as that of glass ; and that a rod of 

 sandstone from Craigleith Quarry expanded very nearly at the 

 same rate as cast-iron. 



The Rev. G. Tough exhibited and described his celestial glass 

 sphere, containing the earth, sun, and moon, with their relative mo- 

 tions. 



Mr Badnall made some observations on the friction upon rail- 

 ways. 



Section B, — Chemistry and Mineralogy. 



The Chemical Section met at eleven a. m. 



The Secretary announced that a set of standard thermometers 

 by the first makers in London, Edinburgh, Paris, and Glasgow, — one 

 of which had been compared with the standard thermometer of the 

 Observatory at Paris, are at present placed by the Royal Society 

 of Edinburgh in the hands of the Council of the Association ; and 

 that an opportunity will be afforded to the members of the Asso- 

 ciation to compare their own thermometers with these, during the 

 week after the close of the meeting, on application being made to 

 the Secretaries of the Chemical or Physical Sections. 



Mr Harcourt then described the objects of the experiments now 

 in progress under his superintendence, for determining the effect of 

 long continued heat on various mineral substances, and the various 

 methods adopted by him in disposing them beneath the iron fur- 

 naces of Yorkshire. 



Dr Clark gave an account of Mr Nixon's process for smelting 

 iron by the aid of the hot-blast, and exhibited numerical results of 

 the advantages derived from the new process. The saving is so 

 great, that the total amount of coal now necessary to produce one 

 ton of iron, amounts only to 2 tons 14 cwt., whereas formerly, it 



